Slub detector



Feb. 1 2, 1952 P. A. DE MARS SLUB DETECTOR Filed Feb. 3. 1949 INVENTOR.

PAUL A DEMARS B$ Patented Feb. 12, 1952 UNITED STATES PATENT- OFFICE SLUB. DETECTOR Paul A. de Mars, Washington, D. 0., assignor, by

mesne assignments, to Raymond M. Wllmotte,

Washington, D".

Application February 3, 1945,. Serial No.. 74,458

-a system for detecting variations in. diameter of yarns, or similar filaments, and which is sufficiently sensitive to. detect variations in cross-section or volume of filamentary materials which are extremely soft and resilient, such as woolen or worsted yarns.

It is still another object of the invention to provide a method and apparatus for the detection of defects in yarn or. the like, the defects consisting of discreet irregularities in cross-section or volume of the yarn, and the system being capable. of operation during any of the various drafting, spinning and winding operations to which the yarns may be subjected prior to weaving.

A further objector the. invention resides in the provision of apparatus for detecting the presence of irregularities in cross-section or volume of. yarn during manufacturing processes, and. for automatically cutting the yarn in response to. detection of a defect.

Another object of the invention resides, in the provision of apparatus for accomplishing any or all of the above objects without the inter-position of electric circuits or sources of electric energy, thereby reducing considerably the total cost of installation of the system. It is a further broad object of the invention to provide a mechanism capable of a forceful, positive action in response to an extremely small mechanical stimulant. v

There have been many attempts made to devise economical and reliable apparatus for detecting defects in yarn during the various drafting, spinning and winding operations which are required v,

an to several inches in length, in which h 1 before deformation of the latter occurs.

volume of material is greater than normal and appears as" a bunch or thickened portion, which, ifnot removed from the yarn will result in a poor or defective fabric. The nature of woolen and worsted fibers makes the detection of sl'ubs difficult, and present devices for the purpose are,

so far as I am aware, not sufficiently reliable to accomplish the desired results. The characteristic of woolen and worsted fibers which makes detection of slubs difficult revolves about the extreme softness and" resilience of the yarn, which causes the yarn to give or compress at the "slub in response to very slight mechanical pressure.

It has been found, from the practical point of view, impossible to construct a reliable mechanical apparatus for detecting slubs as by causing the "'slub to efiect motion of a mechanically triggered arrangement, primarily because no simple reliable mechanically triggered arrangement has been known which is capable of response to the extremely minute force exertable by a slub,

Attempts have been made, for example, to pass yarn suspected of containing slubs through a small aperture, having a cross-section equal to that of the yarn, but smaller than the slub. It has been found impossible to construct a detector operating in this manner which possesses suflicient: delicacy to cause detectable mechanical effects at the aperture in response to the slub, the latter merely compressing to pass as readily through the aperture as does the normal yarn.

A further important consideration revolves about the question of cost. A yarn processing plant normally containsv a large number of spindles, each ofv which requires a slub detector. Slub detectors must, therefore, be relatively inexpensive, if they are to find favor commercially, and must not include electrical wiring, electronic circuits, and the like, for reasons of cost.

Accordingly, in the manufacture of yarn the presence of defects such as slubs has heretofore often been accomplished by visual inspection of the yarn. Such an inspection operation is obviously expensive, and from a practical point of view impossible of being carried out completely. By means of the present invention, the visual inspection. of the. yarn. is completely dispensed, with, he yarn. e ng automatically and continuously inspected by means of extremely simple and economical apparatus, and the yarn being cut automatically in response to detection of a slub so that the slub does not appear in the finished product.

Briefly described, the invention involves a light armature which is normally in contact, at one point thereof, with a magnet, the magnet accordingly providing a force tending to maintain the armature in contact with itself. A spring is provided which biases the armature in such direction as to tend to remove the armature from contact with the magnet, and the amount of biassing force is adjusted to provide a very fine balance of forces. The yarn which is subject to test is passed adjacent to the armature, and preferably substantially in contact therewith, while the yarn is of normal diameter or contains no slubs. The presence of the slubs effects a very slight mechanical impact or pressure against the armature, tending to remove same from contact with the magnet. holding force exerted by the magnet and the Since the balance between the 4 where an extended magnet field is not required. In such magnets the flux density decreases very rapidly with increase of distance from the pole face.

Reference numeral 4 identifies a further column, supported on the base I, to which is secured, intermediate its ends, a flexible armature 5, one end 6 of which is free to move with respect to the support 4. Secured to the upper end 1 of the column d is a bracket 8 which extends over and parallel to the armature 5, and which is provided with a threaded aperture 9 for threadedly engaging a thumb screw 18.

Extending between the armature 5, at a point intermediate the ends thereof and the thumb screw 10, is a helical spring H, which is adjustable in respect to tension exerted thereby by turning the thumb screw i0, and which applies,

5 thus, forces of variable magnitude to the armaforce exerted by the biassing spring are very evenly balanced, the slight impact or pressure provided by the passage of the slubs past the armature is sufficient to cause an extremely slight movement of the armature away from the magnet. The slightest such movement, however, reduces very radically the force which the magnet is capable of exerting against the armature, and, accordingly, the bias force of the spring very rapidly overcomes the holding force of the magnet, and the armature springs away from the magnet.

A further magnet is provided, which tends to pull the armature in the same direction as does the spring, and as the armature is moved away from the first mentioned magnet the force exerted by the second mentioned magnet becomes greater rapidly, and supplements the action of the spring, effecting ultimately a very rapid impact of the armature against itself. Provisions are made for clamping the yarn in response to impact of the armature against the second mentioned magnet, which serves to break the yarn, and to signal an operator, who then effects removal of a length of the yarn suflicient to eliminate the slub.

The various features of noveltywhich characterize my invention are pointed out with particularity in the claims annexed to and forming part of the specification. For a better understanding of the invention, however, of its advantages, of further objects thereof, and of further features thereof, reference may be had to the accompanying drawings and descriptive matter, in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

' Figure 1 is a view in side elevation of a machine constructed in accordance with the invention; and,

Figure 2 is a view in cross-section, taken transversely of Figure l, on the line 2-2.

Referring now more particularly to the drawings, the reference numeral i identifies a base.

for the instrument embodying the present invention. Supported on the base i is a column 2, which supports at its upper end a magnet 3. The magnet 3 is a permanent magnet of the so-called close flux type, which is a type of magnet designed for application where the required pull or holding force is through a zero air gap, i. e., where very little space exists between the magnet poles andthe object, and

ture' 5, in such sense as to tend to remove the end 6 of the armature 5 from direct contact with the permanent magnet 3. The spring I i may be so selected that, upon rotation of the thumb screw l6, its tension may be adjusted to the point where it is just insumcient to break contact between the end 6 and of the armature 5 and the permanent magnet 3.

Further supported on the base i is a pair of standards S, which serve rotatably to support a 'tcylinder I 2, the axis of rotation of which is directly underneath the armature 5, and the digroove 14 serving as a support for a strand of yarn l5 which travels in a direction perpendicular to the axis of the cylinder i2, and is supported by the annular groove 14. By adjustment of the thumb screw 13, any selected portion of the annular groove (4 may be placed in juxtaposition to the armature 5, and the depth of the groove M as it appears immediately under the armature 5 is thus selected to correspond to the desired thickness of the yarn. Accordingly, any slubs 1 in the yarn, upon passing between the annular groove M and the armature 5, exerts a very slight upward pressure on the armature 5. If the balance of forces between the force exerted by the magnet 3 and the force exerted by the spring II is practically identical any slight force is sufiicient to cause a very minute movement of the armature 5 away from the magnet 3. Im mediately any such movement has occurred the force existing between the end .6 of the armature 5 and the magnet 3 is reduced very radically, and the spring H then overcomes the force of themagnet 3 and pulls the armature 5 upwardly and away from contact with the slub.

Supported by the armature 5 is a bracket 16, having a pair of arms I! and I8 which extend respectively in opposite directions laterally with respect to the armature 5, and which are bent slightly so thatthey are located under the yarn 15, one ahead of the annular groove I4, and the other behind it, by reference to the direction of travel of the thread i5. Secured to or integral with the upper surfaces of the arms 41 and i8, respectively, are raised elements 19 and 2B, which cooperate respectively with recesses 2i and 22 formed in the *pole faces 23 and 24' of a horseshoe magnet 25, the latter being supported in any convenient fashion (not shown) with respect to the base I. flux holding type, which is designed to provide a magnetic field which extends to a far greater depth than does the close flux type assembly. Deep flux magnet assemblies are generally longer than close flux assemblies and find application where a pull or holding force must be exerted through a considerable air gap.

In the present application the arms I! and I8 are formed of magnetic material, and, ac cordingly, are subject to an attractive force by the magnet 25. This force is normally relatively slight, but upon release of the armature 5 by the The magnet 25 is of the so-called deep magnet 3, and travel upward of the armature .5

in response to the tension of the spring II, the

arms I! and 18 approach the pole faces 23 and 24 of the magnet 25 suiiiciently to effect generation of a relatively strong upward force by the magnet 25 on the arms l1 and !8, the forceincreasing as the arms I1 and 8 approach more closely to the pole faces 23 and 24. The arms 11 and it are, accordingly, pulled into contact with the pole faces 23 and 24 with considerable force and impact and in so doing the raised portions l9 and 2B clamp the yarn in the recesses 2| and 22. The thread then breaks, permitting removal therefrom of that section thereof which contains the slu Guide posts for the thread are provided in the form of thin wire or tempered glass guide loops 3'!) and 3|, one of which supports the thread as it approaches the slub' detector, and the other of which supports the thread as it leaves the "slub detector, at a sufiicient height such that the thread is not compressed against the annular groove H but travels just barely in contact therewith.

While I have described one form of yarn clarnping and serving arrangement, comprising the magnet 25 and the raised members l9 and 20 supported by the arms I! and i8, and which effectively form an armature for the magnet 25, it will be realized that other forms of thread clamping and severing mechanisms may be adopted in conjunction with the slub detecting structure of the present invention. The form of yarn severing device herein illustrated and described is, however, extremely convenient and economi cal in practice since it involves no electrical circuits, electric power, wiring or the like, and further because of its extreme simplicity.

In the clamping and severing of the yarn, the

trailing edge thereof remains clamped, which is i:

convenient for the operator in retying the severed ends of the yarn. Resetting of the armature may obviously be accomplished by a mere pressure ofthe armature into renewed contact with the ,permanent magnet 3.

While I have described a preferred embodiment of the nivention it will be realized that variations of the specific structure illustrated and described may be resorted to without departing from the true spirit and scope of the invention.

It will be clear that while I have described mt invention as applied to slub detectors, that it essentially corresponds with a sensitive trigger device, responsive to extremely small force: acting over very slight distance, and that while the application of the device to slub detection constitutes a preferred use of the structure, it may be applied to other uses to great advantage.

What I claim and desire to secure by" Letters Patent of the United States is:

I. In apparatus for detecting defective yarn, a close flux magnet, an armature normally in com tact with said close flux magnet, means comprising an open flux magnet for applying force tending to remove said armature from contact with said magnet, said force substantially balancing th attractive force of said close flux magnet for said armature, said armature being movable with respect to said close flux magnet in response only to said applied forcesupplemented by further force generated by contact of defective yarn with said armature.-

2. In apparatus for detecting an extremely small force, a close flux magnet, an armature normally in contact with said close flux magnet, means comprising an open flux magnet for applying force tending to remove said armature from contact with said close flux magnet, said force substantially balancing the attractive force of said close flux magnet for said armature, said armature being movable with respect tosaid close flux magnet in response only to said applied force supplemented by said extremely small force.

3. In apparatus for detecting points of expanded thickness in yarn, an armature in a first predetermined position, stop means adjustable with respect to said armature to provide a mutual separation equal to'a desired yarn thickness, means for passing said yarn between said armature and said stop means, magnetic means for retaining said'armature in said first predetermined posi- .tion, force applying means tending to increase the spacing of said armature from said stop means against the forceof said magnet, said force applying means being just insuflicient to accomplish said increase, and means responsive to passage of a region of expanded thickness in said yarn between said stop means and said armature for supplying a further force adequate to increase said spacing when supplementary to force applied by said force applying means.

4. In apparatus for detecting points of abnormally expanded thickness in a filament, an armature of magnetic material, magnetic means for normally securing said armature in a first predetermined position by the attractive force of said magnetic means, stop means adjustable with respect to said armature to provide a separation between said armature and said stop means, while said armature is secured by said magnetic means. which is equal to a normal filament thickness, means for passing said filament continuously between said stop means and said armature, force applying means tending to accomplish separation of said armature from said magnetic means against the attractive force of said magnetic means, the force applied by said force applying meansbeing just insufficient to accomplish said separation, said abnormally expanded thickness of filament supplying sufiicient additional force to accomplish said separation of said armature from said magnetic means.

5. In apparatus for detecting points of abnormally expanded thickness in a filament, an armature of magnetic material, a close flux magnet for' normally securing said armature in a first predetermined position by the attractive force of said close flux magnet, stop means adjustable with respect to said armature to provide a separation between said armature and said stop means, while said armature is secured by said close flux magnet, which is equal to a normal filament thickness, means for passing said filament continuously between said stop means andsaid armature, force applying means tending to accomplish separation of said armature from said close fiux magnet against the attractive force of said close flux magnet, the force applied by said force applying means being just insufiicient to accomplish said separation, said abnormally expanded thickness of filament supplying sufficient additional force to accomplish said separation of said armature-from said close flux magnet.

6. In force responsive triggering apparatus, a close flux magnet, an armature for said close flux magnet normally maintained in contact with said close flux magnet, first means substantially counter-balancing the force of attraction of said close flux magnet for said armature, and further means comprising an open flux magnet for applying further counter-balancing force to-said armature for separating said armature from said close flux magnet,

' 7. In apparatus for detecting and removing s1ubs-from yarn, an armature comprising magnetic material, magnet means for normally securing said armature in a first predetermined position in response to the attractive force of said magnetic means, stop means adjustable with respect to said armature to provide a predetermined separation between said armature and said stop means, while said armature is secured by said magnetic means, which is equal to a normal yarn thickness in the absence of slubs, means for passing said yarn continuously between said stop means and said armature, force applying means tending to accomplish separation of said armature from said magnet against the attractive force of said magnetic means for said armature, the force applied by said force ap plying means being just insufiicient to accomplish said separation, and passage of said slub between stop means and said armature supplying sufiicient additional force to accomplish said separation of said armature from said magnetic means, yarn clamping meansand means responsive to said force applying means in response to separation of said armature from said magnetic means for actuating said clamping means to clamp said yarn.

8. In apparatus for detecting and removing slubs from yarn, an armature comprising magnetic material, a magnet for normally securing said armature in a first predetermined position in response to the attractive force of said magnet, stop means adjustable with respect to said armature to provide a separation between said armature and said stop means, while said armature is secured by said magnet, which is equal to a normal yarn thickness in the absenceof slubs, means for passing said yarn continu-- ously between said stop means and said armature, iorce applying means tending to accomplish separation of said armature from said magnet, against the attractive force of said magnet for said armature, the force applied by said force applying means being just insufiicient to accomplish said separation, and passage of said slub between said stop means and said armature supplying sufiicient-additional force to accomplish said separation of said armature from said magnet, yarn clamping means secured to said armature means, and means responsive to said force applying means in response to separation of said armature from said magnet for actuating said clamping means to clamp said yarn.

9. In apparatus for detecting and removing slubs from yarn, an armature comprising mag,- netic material, a first magnet for normally securing said armature in a first predetermined position by the attractive force of said first magnet, stop means adjustable with respect to said armature to provide a predetermined separation between said armature and said stop means, while said armature is secured by said first magnet, said separation being equal to yarn thickness in the absence of slubs, means for passing said yarn continuously between said stop means and said armature, force applying means tending to accomplish separation of said armature from said first magnet against the attractive force of said first magnet, the force applied by said force applying means being just insuficient to accomplishsaid separation, and passage of a slub" between said armature and said stop means supplying suificient additional separative force to accomplish said separation of said armature from said first magnet, an open flux magnet, clamping means for said yarn secured to said armature, said open flux magnet being positioned and arranged to apply relatively negligible force to said armature while said armature is secured in said first predetermined position, and to apply radically increased force to said armature upon accomplishment of said separation of said armature from said first magnet. I

10. In apparatus for detecting slubs in yarn, a close flux magnet, an armature for said close flux magnet normally maintained in contact with said close flux magnet, means substantially counter-balancing the force of attraction of said close flux magnet for said armature while said armature is in contact with said close flux magnet, and means responsive to slubs in said yarn for applying further counter-balancing force to said armature for slightly separating said armature from said close fiux magnet, thereby to reduce radically the attractive force of said close flux magnet for said armature.

11. In apparatus for detecting and removing slubs from yarn, a close flux magnet, an armature for said close flux magnet normally maintained in contact with said close flux magnet, means substantially counter-balancing the force of attraction of said close flux magnet for said armature, means responsive to passage of a slub in contact with said armature for applying further counter-balancing force to said armature sufficient for separating said armature slightly from said close flux magnet, thereby reducing radically the attractive force between said close fiux magnet and said armature, and further means operative in response to separation of said armature from said close flux magnet for clamping said yarn.

12. The combination in accordance with the preceding claim wherein said further means comprises an open flux magnet and cooperating clamping means associated respectively with said armature and with said open flux magnet, said open flux magnet being arranged to attract said armature and to actuate said clamping means in response to separation of said armature from said close flux magnet.

v 13. In combination, a magnet, an armature normally in contact with said magnet, means for applying force tending to remove said armature from contact with said magnet, said force substantially balancing the attractive force of said magnet for said armature, said armature being movable with respect to said magnet, said magnet having a field of force which decreases very rapidly with distance from said magnet, and a 9 l0 further magnet exerting upon said armature an UNITED STATES PATENTS attractive force tending to separate said arma- Number Name Date ture from said first mentioned magnet, said fur- 2 103 125 Stoddard 21 1937 th magnet having a field Of force which de- Judson Jan. creases relatively slowly with distance from said a 2229022 Shaw v Jan 1941 further magnet!- 2 2 9 980 11 m Jul I j y 14, 1942 PAUL MARS- 2,425,007 Rouse Aug. 5, 1947 REFERENCES CITED FOREIGN PATENTS The following references are of record in the m Number Co y e file of this patent: 641,196 France Apr. 14, 1938 

